@LukeMorton: You're talking about PLONK as it was called on usenet. I am not sure if you're an older user, but to PLONK was to put someone in a "killfile" which the usenet client would use to magically erase a posters messages from the newsgroup(s).
I am sure there were downsides, but it was a well-used and, I think, well-regarded system.

For almost eight months after launching Stack Overflow to the public, we had no concept of banning or blocking users. Like any new frontier town in the wilderness of the internet, I suppose it was inevitable that we'd be obliged to build a jail at some point. But first we had to come up with so...